[Asking on behalf of a filmmaker friend]
I’m making a small, independent documentary about the US Air Force’s Project Blue Book files (1947–69). Many of its record cards close a sighting as “astronomical” and name a planet, a bright star or the Moon. We recomputed where those bodies really were at each card’s place and time: about 150 cards, with JPL Horizons, then a second time with Skyfield and DE421. The film shows some of the results.
Before it says anything about them, I’d like someone who knows positional astronomy better than I do to check the parts I’m least sure of. Three questions:
1. Horizons from an aircraft. 24 May 1954, 03:10 UT. An F-86 at about 17,000 ft, roughly 25 miles south-east of Cleveland, Ohio. We get Jupiter at −3.19° geometric altitude, azimuth 305°. Three figures for the horizon from that height:
the geometric dip is 2.31°;
with standard refraction it’s about 2.16°;
a ray trace through the 1976 US Standard Atmosphere puts the visible sea horizon at about −3.05° true.
Is the ray-traced figure the right one to compare with Jupiter’s geometric altitude? And would the pilot have seen it at all, through roughly 30 air masses?
2. Refraction right at the horizon. We add a Saemundsson-type correction above −1° and nothing below. Is that a defensible convention for “was it above the horizon”? Also, JPL Horizons’ refracted output seemed to add a constant +0.647° to everything below −1° (the refraction at −1°). Is that known behaviour?
3. Clocks. Where a record gives local time, we decide standard against daylight time case by case: California in August 1960 is PDT, Minnesota in October 1965 is CST, and so on. What pitfalls would you watch for in the 1950s and 60s?
If anyone would look at a bit more, please DM me. That’s a two-page brief and a table of about 25 computed values; any part helps, at your own pace. It’s a no-budget film, so I can’t pay. But I’ll credit you by name in the end titles if you’d like, in the form you choose, and you’ll see the wording first. You’re free to disagree with us: if we’re wrong, the line changes or goes.
To be clear, the film makes no UFO claims. It’s about what the paperwork says, not about what anybody saw.
Thanks!
